1. Field of the Invention
Liquid fuel production by fermentation of cellulosic materials has been recognized in the production of ethanol. In recent times, the worldwide energy shortage has furthered consideration and improvement of non-fossil sources of energy. Biological materials and organic wastes, represent a large renewable potential energy resource. This invention relates to improved liquefaction from organic materials by hybrid biological-thermal liquefaction to provide substantially increased conversion to alcohol containing fuels of the organic component of the feed material, including terrestrial and aquatic energy crops, organic wastes and peat. The process of this invention provides fermentation of an organic carbonaceous feed producing alcohol containing liquid fuel followed by thermochemical conversion of the fermentation residue and plant portions not used for fermentation, the thermochemical conversion providing product gas or liquid, a portion of which or a derivative thereof, such as ammonia or hydrogen, may be supplied to the fermentation reactor for improved fermentation. Product gas from thermochemical conversion may also be converted to liquid fuels by catalytic synthesis or product liquids from thermochemical liquefaction may be separated or upgraded to provide alcohol containing liquid fuel. The thermal residue from such gasification or liquefaction may be recycled to the fermentation reactor to provide phosphorus and other inorganic nutrients. The hybrid bio-thermal liquefaction process of this invention broadens the range of organic feeds suitable for conversion, provides higher liquid fuel production per pound of organic feed, and substantially reduces the quantity of residue from the process over currently known processes. The hybrid bio-thermal liquefaction process of this invention may additionally provide medium Btu fuel gas, ammonia and hydrogen containing gas for a variety of uses. Thermal energy from the thermal conversion may advantageously be used in other steps of the process, such as distillation, pretreatment, fermentation or dewatering, providing an overall high energy efficiency.